Timepiece resonator mechanism with a pivoting weight pivoting about a virtual axis, and comprising a flexure pivot mechanism and a first and second fixed support to which is attached, by a first resilient assembly and respectively a second resilient assembly which together define the virtual axis, a rotary support carrying the pivoting weight, this flexure pivot mechanism is planar, the first resilient assembly includes, on either side of the virtual axis, a first outer flexible strip and a first inner flexible strip, joined to each other by a first intermediate strip stiffer than each of the latter, together defining a first direction passing through the virtual pivot axis, and the second resilient assembly includes a second flexible strip defining a second direction passing through the virtual pivot axis.